In fact, let me answer your very first question, and maybe you will get the hang of things once you take the time to look at the themes options pages.
Ok i Have the mystique.2.4.2 theme installed on my site and i want to change the background colors how can i do it HELP!!!!
Dashboard > Appearance > Mystique settings > >Design tab >
6th option down on the page. See where it says: “Background color” ?
Give that a go first, and see if it sets things in motion for you. Click it, drag your cursor over a new color and then set the new background color and test it.(Don’t forget to click the “Save Changes” tab, at the top of the page first). Then you can take a minute to explore the rest of the theme options pages.